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REACTION_PRESSURE
This keyword data block is used to define pressure during batch-reaction steps. This data block can also be used to specify the pressure in a cell or range of cells during advective-transport calculations (
ADVECTION
) and advective-dispersive transport calculations (TRANSPORT).
Example data block 1
Line 0: REACTION_PRESSURE 1 Three explicit reaction pressures.
Line 1: 1.0 250.5 500.0
Explanation 1
Line 0:
REACTION_PRESSURE
[
number
] [
description
]
REACTION_PRESSURE
is the keyword for the data block.
number
--Positive number or a range of numbers to designate this pressure definition. A range of numbers may be given in the form
m-n
, where
m
and
n
are positive integers,
m
is less than
n
, and the two numbers are separated by a hyphen without intervening spaces. Default is 1.
description
--Optional comment that describes the pressure data.
Line 1:
list of pressures
list of pressures
--A list of pressures (atm) that will be applied to batch-reaction calculations. More lines may be used to supply additional pressures. One batch-reaction calculation will be performed for each listed pressure.
Example data block 2
Line 0: REACTION_PRESSURE 1 Three implicit reaction pressures.
Line 1: 1.0 500.0 in 3 steps
Explanation 2
Line 0:
REACTION_PRESSURE
[
number
] [
description
]
Same as Example data block 1.
Line 1: pres
1
,
pres
2
,
in
steps
pres
1
--Pressure of first reaction step, atm.
pres
2
--Pressure of final reaction step, atm.
in
steps
--“
in
” indicates that the pressure will be calculated for each of
steps
number of steps. The pressure at each step,
i
, will be calculated by the formula
; if
steps
= 1, then the pressure of the batch reaction will be 
. Example data block 2 performs exactly the same calculations as Example data block 1. If more batch-reaction steps are defined by KINETICS, REACTION, or REACTION_TEMPERATURE input, the pressure of the additional steps will be pres
2
.
Notes
If more batch-reaction steps are defined in KINETICS, REACTION, or REACTION_TEMPERATURE than pressure steps in
REACTION_PRESSURE
, then the final pressure will be used for all of the additional batch-reaction steps. INCREMENTAL_REACTIONS keyword has no effect on the
REACTION_PRESSURE
data block. The default pressure of a reaction step is equal to the pressure of the initial solution or the mixing-fraction-averaged pressure of a mixture.
REACTION_PRESSURE
input can be used even if there is no REACTION input. The method of calculation of pressure steps using “
in
” is slightly different than that for reaction steps. If
n
pressure steps are defined with “
in
n
” in a
REACTION_PRESSURE
data block, then the pressure of the first reaction step is equal to
pres
1
; pressures in the remaining steps change in
n-1
equal increments. In contrast, if
n
reaction steps are defined with “
in
n
” in a REACTION data block, then the reaction is added in
n
equal increments.
In an advective-transport calculation (
ADVECTION
), if
REACTION_PRESSURE
n
is defined (or a range is defined
n
-
m
), and
n
is less than or equal to the number of cells in the simulation, then the first pressure in the data block of
REACTION_PRESSURE
n
is used as the pressure in cell
n
(or cells
n
-
m
) for all shifts in the advective-transport calculation. In advective-dispersive transport simulations (TRANSPORT), the initial equilibration also occurs at the first pressure of
REACTION_PRESSURE
n
in cell
n
.
Example problems
The keyword
REACTION_PRESSURE
is used in example problem 2.
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